Restore Your Truck’s Performance and Reliability
Is your dependable GMC or Chevy truck suddenly giving you headaches? A faulty Powertrain Control Module (PCM), the vehicle’s main computer, is often the culprit behind frustrating issues like poor starting, erratic shifting, and a persistent Check Engine Light. Getting back on the road shouldn’t mean a costly trip to the dealership. This is a reliable, tested, and pre-programmed replacement PCM that gets your vehicle running correctly without the hassle.
This isn’t just a part in a box. It’s a complete solution. We take this genuine GM engine computer, sourced from a salvaged vehicle, and flash it with the latest official GM software specific to your truck’s Vehicle Identification Number (VIN). This critical step ensures that when you receive the part, it’s ready to communicate perfectly with your engine, transmission, and all other systems. For anyone tackling this job in their own garage, this service is the key to a successful and straightforward repair. A faulty computer can bring your workhorse to a halt, but this direct-fit 1998-1999 GMC 3500 PCM is the answer to restoring its function and your peace of mind.
A Technician’s Notebook: The Ghost in the Machine
I once had a ’99 Chevy 2500 in my bay with an intermittent misfire on cylinder 3. The owner had already replaced the plug, wire, cap, rotor, and even the fuel injector. The misfire persisted. Standard diagnostics showed a weak injector pulse, but only sometimes. Instead of chasing electrical gremlins down the harness, I checked the source: the PCM. The injector driver circuit inside the old computer was failing under heat. After swapping in a properly programmed PCM like this one, the truck ran perfectly. It’s a classic example of how a failing PCM can send you down a rabbit hole of replacing perfectly good parts. This is why diagnosing the computer first can save hundreds in parts and labor.
Is Your Vehicle Showing These Signs of PCM Failure?
- ✔ Check Engine Light is on with codes like P0601 (Internal Control Module Memory Check Sum Error) or other P06xx communication faults.
- ✔ The engine cranks but refuses to start.
- ✔ Harsh or erratic automatic transmission shifting.
- ✔ A noticeable drop in fuel economy for no apparent reason.
- ✔ The engine stalls unexpectedly while driving or at idle.
- ✔ Communication issues with your scan tool.
A Straightforward Guide to Installation
Installing your pre-programmed 1998-1999 GMC 3500 PCM is a job most DIYers can handle with basic tools. Our VIN programming service handles the most complex part for you.
- Safety First: Always disconnect the negative terminal from your vehicle’s battery and wait about 10 minutes to ensure all systems are powered down.
- Locate the PCM: On most of these trucks and vans, the PCM is located in the engine compartment, typically on the driver’s side fender well or near the firewall.
- Disconnect the Harnesses: Carefully unclip and remove the large electrical connectors from the old PCM. Inspect the pins for any corrosion or damage before proceeding.
- Remove the Old Module: Unbolt the old PCM from its mounting bracket. It’s usually held in place by a few small bolts.
- Install the New Module: Mount your new PCM onto the bracket and securely reconnect the electrical harnesses. You should hear a ‘click’ as they lock into place.
- Reconnect the Battery: Re-attach the negative battery terminal.
- Perform Security Relearn (If Needed): In many cases, you may need to perform a simple security relearn procedure, which typically involves turning the key to the ‘ON’ position for 10-15 minutes. This allows the new PCM to sync with your vehicle’s anti-theft system. Consult your vehicle’s service information for the exact procedure.
Guaranteed Fitment for Your GM Vehicle
This module is a direct replacement for service number 09366810 and is interchangeable with several other part numbers. It is confirmed to fit the following vehicles when equipped with the gasoline engine and matching the service ID 9355699. Please verify your original part number or contact us with your VIN to ensure compatibility.
CHEVROLET 2500 PICKUP 98-99
CHEVROLET 3500 PICKUP 98-99
GMC 1500 PICKUP 98-99
GMC 2500 PICKUP 98-99
GMC 3500 PICKUP 98-99
CADILLAC ESCALADE 99
CHEVROLET ASTRO 98
CHEVROLET BLAZER S10 98
OLDSMOBILE BRAVADA 98
CHEVROLET EXPRESS 1500/2500/3500 VAN 98-99
GMC SAVANA 1500/2500/3500 VAN 98-99
GMC ENVOY 98
ISUZU HOMBRE 98 (4.3L)
GMC JIMMY S15 98
GMC SAFARI 98
CHEVROLET S10 / GMC SONOMA 98 (4.3L)
CHEVROLET SUBURBAN 1500/2500 98-99
CHEVROLET TAHOE 98-99
GMC YUKON 98-99
Frequently Asked Questions About This PCM
Why do you need my VIN?
Why do you need my VIN?
Your VIN (Vehicle Identification Number) is essential. It allows us to load the exact, correct GM factory software for your truck’s specific engine, transmission, and options. This ensures a true plug-and-play installation and optimal performance, saving you a trip to the dealer for programming.
Is this part difficult to install?
No, for someone with basic mechanical skills, it’s a very manageable job. Since we pre-program the module, the most complicated part is already done. The physical swap usually involves disconnecting the battery, unplugging a few connectors, and removing a few bolts. See our installation guide above for the basic steps.
Will I need to perform any other procedures after installation?
For some vehicles, a security relearn (Passlock/VATS) and a Crankshaft Variation Relearn (CASE) may be necessary. The security relearn is often a simple key-on procedure. The CASE relearn requires a capable scan tool and synchronizes the PCM with the crankshaft position sensor to prevent misfire codes. We recommend checking your vehicle’s specific requirements.
This is a used part. How can I be sure it’s reliable?
Each module is sourced from a salvaged vehicle and thoroughly inspected and tested to ensure it is fully functional. We then flash it with the latest stable software from GM. This provides a dependable, factory-level solution at a fraction of the cost of a new unit.
My part number is slightly different, but my truck is on the list. Will it work?
Yes. This PCM, identified by service ID 9355699, supersedes and is interchangeable with many part numbers, including 09366810, 16266645, 16250279, and others. As long as your vehicle is on our compatibility list, our VIN-specific programming will ensure it functions correctly.